Here is the situation. I briefly mounted my H100 onto my i5, and then decided to unmount the cooler and modify my case. After pulling off the cooler, I can see ripples and valleys in the paste. However, I never heated the paste. It was simply a dry run. I'm pretty sure I have some A5 sitting at the bottom of a box somewhere, but it seems a little silly cleaning and re-apply the paste when it was never actually used. If you don't apply heat can you re-use the paste? What's the difference between unused paste on a cpu, and unused paste in a bottle?

Update: The thread consensus is, no you can't. Even though heat has not "cured" the paste, exposure to air (24hrs+) may have dried it. This will make re-application difficult to remove air bubbles. Expect slightly higher temps.Edited by Runamok81 - 9/5/12 at 7:35pm

The H100 ships with plenty of paste. I didn't lose any of it. .... hmmm... I guess it comes down to how lazy I am. 1-2 degrees difference is enough to dissuade me from doing it. I suppose I could just slap it on, test for a bit. Then apply A5, test, and post the results.

Here is the thing. Yes you can just stick it back together and it will work. As others have mentioned though it isn't advisable though because of the air bubbles. My advice though would be to just clean it off the block and spread it thin with a card on the cpu. They generally apply to much anyways with the Hydro series.

No difference between whats in the bottle and what is on the blocks. The only time it would matter if it is thermal glue rather just paste in which it has a cure time and hardens at a certain time. As a heads up I believe they are still using Shin-Etsu on the Hydro series which is a great thermal paste.